LineRenderer——line drawing function

1、LineRenderer

LineRenderer is a component provided by Unity for drawing lines. It can be used to draw line segments in the scene. It can generally be used for

• Draw attack range
• weapon infrared
• Accessibility
• Other line drawing functions

An object can only be bound to one LineRenderer component

2. LineRenderer parameters related

Loop	Whether the starting point and the starting point are always connected
Positions	The point coordinates of the line segment (usually the world coordinate system, adjusted through Use World Space), you can draw a circle by increasing the number of points and controlling the code Line segment width adjustment (not point-to-point width adjustment, but from start to end)
Color	Color change, you can change the gradient effect of color
Corner Vertices (corner vertex, fillet)	How many extra points are used when drawing corners in a line (that is, when the line segment turns). Increasing this value can make the line corners look smoother.
End Cap Vertices (terminal vertex, fillet)	Adjust the end point fillet
Alignment	Alignment	View: viewpoint, line segment facing the camera
		Transform Z: The line segment faces its Z axis
Texture Mode	Texture mode, used according to the material	Stretch: Stretch, map the texture once along the entire line
		Tile: tiling, repeated texture
		Distribute Per Segment: Distribute execution
		Repeat Per Segment：Repeat display
Shadow Bias	shadow offset
Generate Lighting Data	Generate light source data (if the material will be affected by the light source, it needs to be turned on to display normally)
Use World Space	Whether to use the world coordinate system
Materials	The shader used for the line
Lighting	Care for the impact		Cast Shadows: Whether to turn on shadows
			Receive Shadows: Receive
Probes	light probe		Light Probes: Light detector mode off: Do not use light probe Blend Probes: Using interpolated light probes Use Proxy Volume: Use a 3D grid to interpolate light probes Custom Provided: Customization is determined by the material
			Reflection Probes: reflection probe mode Almost the same as Use Probes, except for two things: Blend Probes And Skybox: Use blended reflection probes and blend them with the skybox Simple: Enable normal probes, overlapped probes are not mixed
Additional Settings	Additional settings		Motion Vectors: motion vectors Camera Motion Only: Use camera motion to track motion Per Object Motion: Track motion for a specific object Force No Motion: Do not track
			Dynamic Occlude: dynamic occlusion culling
			Sorting Layer: Sorting albums
			Order in Layer: The order of line segments in the sorting layer

3. LineRenderer code related

// 动态添加一个线段
GameObject line = new GameObject();
line.name = "Line";
LineRenderer lineRenderer = line.AddComponent<LineRenderer>();

// 首位相连
lineRenderer.loop = true;

// 开始结束的宽
lineRenderer.startWidth = 0.03f;
lineRenderer.endWidth = 0.02f;

// 开始结束的颜色
lineRenderer.startColor = Color.white;
lineRenderer.endColor = Color.red;

// 设置材质
lineRenderer.material = Resources.Load<Material>("material");

// 设置点，一定要设置点的个数,然后设置点的位置
// 同时设定了点的数量后，如果少于已有点的数量，会将多余的点删掉
lineRenderer.positionCount = 4;
// 通过数组批量设置
lineRenderer.SetPositions(new Vector3[] {new Vector3(0, 0, 0),
                                         new Vector3(0, 0, 5),
                                         new Vector3(5, 0, 5)};
// 注意，如果设置的点的数量与插入点位置的数量不一致，那么最后会补齐一个坐标为（0，0，0）的点
// 通过索引设定第(index+1)个点的坐标
lineRenderer.SetPostion(3, new Vector3(5, 0, 0));

// 是否使用世界坐标系，决定了是否随对象而移动
lineRenderer.useWorldSpace = false;

// 让线段会受光的影响，进行着色器计算
lineRenderer.generateLightingData = true

•  If you want to draw a circle:

public void DrawCircle(Vector3 centerPos, float r, int pointNum) {
    GameObject obj = new GameObject();
    obj.name = "circle";
    LineRenderer line = obj.AddCompoent<LineRenderer>();
    line.loop = true;
    line.positionCount = pointNum;

    float angle = 350f / pointNum;
    for(int i = 0; i < pointNum; ++i) {
        // 1、点+向量 => 平移点
        // 2、 四元数* 向量 => 旋转向量
        line.SetPosition(i, centerPos + Quaternion.AngleAxis(angle * i, Vector3.up) * Vector3.forward * r)
    }
}

• Long press the mouse to get the trajectory of the mouse movement

• private Vectore3 nowPos;
  
  private void Update() {
      if (Input.GetMouseButtonDown(0)) {
          GameObject obj = new GameObject();
          obj.name = "trace";
          LineRenderer line = obj.AddCompoent<LineRenderer>();
          line.positionCount = 0;
          line.loop = false;
          line.starWidth = 0.5f;
          line.endWidth = 0.5f;
      }
  
      if (Input.GetMousePosition(0)) {
          line.positionCount += 1;
  
          nowPos = Input.mousePosition;
          nowPos.z = 10;        // 设定屏幕的横截面，即画线的平面
  
          Camera.main.ScreenToWorldPoint(Input.nowPos);
  
          line.sSetPostion(line.positionCount - 1, 
      }
  }